Minimally Invasive Retractor with Separable Blades and Methods of Use

ABSTRACT

A device, system and method for orthopedic spine surgery using a screw-based retractor, are disclosed herein and allows for access to the spine through a minimally or less invasive approach. The retractor device is designed to be coupled to a pedicle screw and then to have opposed arms of the retractor spread apart to open the wound proximally. The retractor is removed by separating the opposed blades to allow the retractor portions to be pulled out of the wound. The retractor is intended to be made of a flexible metal material, sterile packaged and disposable after one use. A system and method for using the retractor and performing a minimally invasive spine surgical procedure are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to, and the benefit of, U.S.Provisional Application Ser. No. 61/032,199 filed Feb. 28, 2008, theentire contents of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to orthopedic spine surgery andin particular to a minimally invasive retractor with separable bladesand methods for use in a minimally invasive surgical procedure.

2. Background of the Technology

There has been considerable development of retractors and retractorsystems that are adapted for use in less invasive procedures. Many ofthe recent developments are based on traditional types of surgicalretractors for open procedures, predominantly table-mounted devices ofvarious designs. These devices tend to be cumbersome and are not welladapted for use in small incisions. Standard hand-held surgicalretractors are well known in the prior art and can be modified to fitthe contours of these small incisions, but they require manualmanipulation to maintain a desired placement, thereby occupying one handof the physician or requiring another person to assist the physicianduring the procedure. Typical retractors are also positioned into thesoft tissue and are levered back to hold the wound open, frequentlyrequiring re-positioning if they dislodge, obstruct the physician'sview, or interfere with access to the surgical site.

In recent years, minimally invasive surgical approaches have beenapplied to orthopedic surgery and more recently to spine surgery, suchas instrumented fusions involving one or more vertebral bodies. Unlikeminimally invasive procedures such as arthroscopic knee surgery orgallbladder surgery where the affected area is contained within a smallregion of the body, spinal fusion surgery typically encompasses aconsiderably larger region of the patient's body. In addition,arthroscopic surgery and laparoscopic surgery permit the introduction offluid (i.e. liquid or gas) for distending tissue and creating workingspace for the surgeon. Surgery on the spine does not involve a capsuleor space that can be so distended, instead involving multiple layers ofsoft tissue, bone, ligaments, and nerves. For these reasons, the idea ofperforming a minimally invasive procedure on the spine has only recentlybeen approached.

By way of example, in a typical spine fusion at least two vertebralbodies are rigidly connected using screws implanted into the respectivevertebral bodies with a solid metal rod spanning the distance betweenthe screws. This procedure is not generally conducive to a minimallyinvasive approach. The insertion of pedicle or facet screws isrelatively straightforward and can be accomplished through a minimalincision. The difficulty arises upon the introduction of a length of rodinto a very small incision with extremely limited access and visibility.A single level fusion may require a 30-40 mm rod to be introduced into a1 cm incision and a multilevel fusion may require a rod several incheslong to fit into a 1 cm incision. For this reason, it is important thatthe minimal incision be maintained in an open and accessible condition(i.e. as wide as practicable) for introduction of the rod.

Minimally invasive surgery offers significant advantages overconventional open surgery. First, the skin incision and subsequent scarare significantly smaller. By using more than one small incision ratherthan one large incision, the need for extensive tissue and muscleretraction may be greatly reduced. This leads to significantly reducedpost-operative pain, a shorter hospital stay, and a faster overallrecovery.

Most spine implant procedures are open procedures, and while manymanufacturers advertise a minimally invasive method, the procedure istypically not recommended for fusions and focuses on more common andaccepted minimally invasive spine procedures such as kyphoplasty,vertebroplasty, and discectomy.

Medtronic Sofamor Danek's SEXTANT® is a minimally invasive device usedfor screw and rod insertion. Its shortcomings lie with how complicatedthe system is to use and the requirement for an additional incision forrod introduction. This system also requires that the guidance devices berigidly fixed to the pedicle screw head in order to maintain instrumentalignment and to prevent cross-threading of the setscrew. For thesereasons, the surgeon cannot access the surrounding anatomy for completepreparation of the field. Nor does SEXTANT® allow for any variation inthe procedure, if need be.

Depuy Spine's VIPER™ system is another minimally invasive implant andtechnique recommended for one or two level spine fusions. This system isless complicated than the SEXTANT®, only requiring two incisions for aunilateral, one-level fusion, but it is limited in the same way as theSEXTANT® because it also requires the instrumentation to be rigidlyfixed to the pedicle screw.

Spinal Concept's PATHFINDER® and NuVasive's SPHERX® spinal system (asdisclosed in U.S. Pat. No. 6,802,844), are marketed as “minimallydisruptive” spine fusion implants and procedures. While they haveadvantages over a general “open” procedure, they do not provide all ofthe advantages of a truly minimally invasive approach. Theircharacterization as “minimally open” procedures is a result of theinherent difficulty of introducing a rod in a minimally invasive spinalprocedure. In order to introduce a rod long enough to accomplish asingle level fusion, these systems describe an incision long enough toaccept such a rod, thereby undermining the advantages of a minimallyinvasive approach.

The problem of rod introduction warrants further discussion as it is thecentral problem in minimally invasive spinal fusions. The systemscurrently on the market address this issue by adding another incision,using a larger incision, or avoiding fusions greater than one level.

In order to be truly minimally invasive, a spine fusion procedure shouldhave a minimum number of small incisions and not require significanttissue and/or muscle retraction. Furthermore, an improved approachshould encompass as many variations and applications as possible therebyallowing the surgeon to adjust the procedure to accommodate the anatomyand surgical needs of the patient as presented. For instance, spinalfusions should not be limited to just one or two levels.

Therefore, a continuing need exists for an improved device, an improvedsystem, and an improved method for performing minimally invasive spinesurgery.

SUMMARY

The present disclosure relates to a device, a system, and a method for ascrew-based retractor used in performing minimally invasive spinesurgery. The retractor is removably attached to a pedicle bone screwthat is used to guide the retractor into place and act as a point offixation with respect to the patient. Multiple retractors may be used inconjunction with a single screw to allow retraction in multipledirections and multiple retractors may be used with multiple screws,respectively, during a single spine procedure. The retractor may bemanufactured for a single use or can be sterilized and reused. Finally,the retractor may also act as a guide that will aid in the insertion ofinstruments and implants.

In its nominal position, the retractor extends longitudinally from thescrew in a generally cylindrical shape with at least one retractingblade. Instrument holes are located perpendicular to the long axis ofeach retracting blade whereby a standard surgical instrument, such as aGelpi retractor, can be used to separate the blades to retract the skinand soft tissue and maintain the field of view as well as a site forperforming surgical procedures. Yet, where the retractor is connected tothe pedicle screw the retractor maintains a substantially circularcross-section. Since the retractor is not permanently fixed but isremovably attached to the pedicle screw, it is free to have polyaxialmotion allowing the surgeon greater wound access and freedom to operate.Furthermore, polyaxial motion allows the retractor to expandmedial-laterally as well as cephalad-caudally and any combinationthereof. This freedom of movement proximally and non-rigid attachmentdistally decreases the need for retractor re-positioning during aprocedure. Proximal stabilization of the retractor is possible when itis used in conjunction with either a free standing or table-mountedretractor.

The minimally invasive retractor can be designed to flex proximal ordistal to the pedicle screw head. In one embodiment, the retractor has a“living hinge” and an opposing “true hinge” incorporated into theretractor's blade design. In a further embodiment, the minimallyinvasive retractor has a pair of living hinges. In an alternateembodiment, the minimally invasive retractor has a pair of true hinges.

As viewed along its longitudinal axis, a cross-section of the minimallyinvasive retractor has a generally circular configuration and providesadditional stiffness. The geometry of the minimally invasive retractorprovides sufficient stiffness for maintaining the opening at thesurgical site.

Minimally invasive retractors having combinations of a living hingeand/or a true hinge may include at least one window that is aligned withthe pedicle screw saddle and allows the insertion of instruments intothe surgical site or added visualization.

The distal tip of the minimally invasive retractor is bullet shaped toaid in insertion through the soft tissue to where it will seat againstthe pedicle. The distal tip comprises a pair of opposed arms that may beselectively interlocked by one or more retractable pins. The distal tipmay also have one or more relief features cut into it to aid in removingthe retractor. Upon completion of the procedure, the retractable pin canbe removed to permit separation of the opposing arms of the distal tip.In this manner, the distal tip can be separated so that the separatedretractor portions (two or more) can be pulled out of the wound past thescrew and rod assembly. Advantageously, by positioning the distal tip ofthe retractor around the head of the screw adjacent the bone, theretractor retracts soft tissue from a point adjacent or below the headof the screw, creating excellent visibility of the screw and surroundingtissue. If relief features are included, the distal tip of the retractorportions flexes to facilitate removal past the screw assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the presently disclosed minimally invasive retractor aredescribed herein with reference to the accompanying drawings, wherein:

FIG. 1A is a perspective view of a minimally invasive retractoraccording to an embodiment of the present disclosure;

FIG. 1B is a perspective view of the minimally invasive retractor ofFIG. 1A rotated 180°;

FIG. 2 is a bottom view of the minimally invasive retractor of FIGS. 1Aand 1B;

FIG. 3 is a side view of the minimally invasive retractor of FIGS. 1Aand 1B;

FIG, 3A is an enlarged detail view from FIG. 3 of the minimally invasiveretractor;

FIG. 4 is a side view of a minimally invasive retractor according toanother embodiment of the present disclosure;

FIG. 4A is an enlarged detail view from FIG. 4 of the minimally invasiveretractor;

FIG. 5 is a top view of a minimally invasive retractor according toanother embodiment of the present disclosure;

FIG. 6 is a side view of a minimally invasive retractor and screwassembly including the minimally invasive retractor of FIGS. 1A and 1B;

FIG. 7 is a perspective view of the minimally invasive retractor andscrew assembly of FIG. 6;

FIG. 8 is an enlarged detail view from FIG. 6 of the minimally invasiveretractor and screw assembly; and

FIG. 9 is a front cross-sectional view of a vertebral body with a pairof minimally invasive retractors attached using screws with the bladesin their initial position and rods positioned in the passages of theminimally invasive retractors.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the presently disclosed minimally invasive retractiondevice will now be described in detail with reference to the drawingswherein like reference numerals identify similar or identical elements.In the drawings and in the description which follows, the term“proximal”, as is traditional, will refer to the end of the minimallyinvasive retraction device which is closest to the operator while theterm “distal” will refer to the end of the device which is furthest fromthe operator.

The present disclosure relates to a device, a system, and a method for ascrew-based retractor used in performing minimally invasive spinesurgery. Such a device, system, and method is disclosed in U.S. patentapplication Ser. No. 11/528,223 filed on Sep. 26, 2006 (U.S. PatentApplication Publication No. 2007/0106123), the entire contents of whichare incorporated herein by reference.

Referring intially to FIGS. 1A, 1B, and 2, an embodiment of thepresently disclosed minimally invasive retractor or retractor isillustrated and generally designated as 10. Retractor 10 includes anopen proximal end 12 and a distal end 14. In addition, retractor 10includes a pair of retractor blades 8 a, 8 b having a plurality ofinstrument holes 6 disposed on each of retractor blades 8 a, 8 b.Instrument holes 6 are configured and dimensioned to cooperate withdifferent surgical instruments (e.g., a Gelpi retractor). A distalregion 9 of retractor 10 includes an opening 7 (FIG. 2), optionally atleast one slot or window 2, and a pair of arms 13 a, 13 b. As shown inFIG. 1A, arm 13 b extends from distal end 14 to a hinged area or truehinge 5. FIG. 1B shows retractor 10 of FIG. 1A rotated 180° toillustrate arm 13 a extending from distal end 14 to a flexible region orliving hinge 4. Optional window 2 may be sized and configured to receiveinstruments therethrough and/or provide for visual inspection. Retractorblades 8 a and 8 b are attached to living hinge 4 and true hinge 5,respectively, to define a substantially continuous elongate member. Apair of recesses 4a is formed between retractor blade 8 a and arm 13 ato define living hinge 4. Arm 13 b is joined to distal region 9 by apivot pin 11 that is adapted to enable pivoting movement of retractorblade 8 b relative to arm 13 b during use of retractor 10, as will bediscussed in detail hereinafter. A pair of recesses 5 a is formedbetween retractor blade 8 b and arm 13 b to further define true hinge 5.Alternatively, retractor 10 could have two living hinges or two truehinges.

Optionally, distal end 14 may further include at least one relief regionR (FIG. 2) defined by at least one slit 16 extending proximally fromopening 7 (FIG. 2). Optional slit 16 may originate at window 2 andextend distally towards opening 7. It is contemplated that otherarrangements of relief structures may be used to define optional reliefregion R and these may exist between opening 7 and window 2. Each slit16 is a weakened portion of distal end 14. It may be a score in thematerial, a perforated region in the material, or another structuralarrangement allowing relief region R to be radially displaced away fromthe centerline of retractor 10 in response to applied forces. Inaddition, distal end 14 has a generally convex outer surface thatfacilitates insertion of retractor 10 through layers of body tissue.

Retractor blades 8 a, 8 b and arms 13 a, 13 b are generally arcuatestructures that cooperate to define segments of a substantially circularcross-sectional configuration for retractor 10. Preferably, eachretractor blade 8 a, 8 b and each arm 13 a, 13 b have an arcuateconfiguration that is less than about 180° and are radially spaced apartto define a continuous slot 17 along a substantial portion of retractor10. In addition, each retractor blade 8 a, 8 b and its corresponding arm13 a, 13 b define a passage 18 that also extends substantially theentire length of retractor 10. Passage 18 is expandable, as will bediscussed in detail hereinafter, for receiving a rod 3 (FIG. 9) therein.Retractor blades 8 a, 8 b and arms 13 a, 13 b define segments of asubstantially circular ring shape in cross-section, thereby providingsufficient stiffness (i.e., rigidity) such that retractor blades 8 a, 8b and arms 13 a, 13 b resist bending from the counter forces of theretracted tissues.

Opening 7 is located at distal end 14 of retractor 10 and is sized forreceiving the shank of a threaded screw 40 (FIGS. 6-8) therethrough, butinhibiting passage of a head 42 (FIG. 7) of screw 40 so as to supportscrew 40 at distal end 14 of retractor 10. The interior surface ofdistal end 14 has a generally concave spherical geometry that is adaptedto mate with head 42 of pedicle screw 40.

Referring now to FIGS. 2, 3, and 3A, arms 13 a and 13 b are configuredand dimensioned to releasably interlock to form the generally convexouter surface of distal end 14. More specifically, a pair of opposedfingers 21 a, 21 b are in spaced relation to each other and extend fromarm 13 b such that a finger 22 extending from arm 13 a is receivedbetween fingers 21 a, 21 b to interlock arms 13 a and 13 b, i.e., in aninterlocked position, as illustrated in FIG. 3A. A pair of substantiallyaligned throughbores 23 a and 23 b are defined through fingers 21 a and21 b, respectively. In the interlocked position of arms 13 a, 13 b, athroughbore 23 c defined through arm 22 is configured to substantiallyalign with throughbores 23 a and 23 b to further define a pin receptacle23. Pin receptacle 23 is sized for receiving a retractable pin 15therethrough as indicated by directional arrow B, but inhibiting passageof a head 15 a of retractable pin 15 so as to support retractable pin 15at distal end 14 of retractor 10 to maintain arms 13 a and 13 b in theinterlocked position. As shown in FIG. 3A, retractable pin 15 may beremoved from interlocking receptacle 23 as indicated by directionalarrow A to allow arms 13 a and 13 b to be separated from each other asindicated by directional arrows C and D. In the illustrated embodiment,a tether 19 is shown operably connected to pin head 15 a. In use, tether19 may be used to pull pin 15 in the direction indicated by directionalarrow A to remove pin 15 from interlocking receptacle 23. In otherembodiments, an elongated tool may also be used to manipulate pin 15relative to interlocking receptacle 23. Once pin 15 is removed frominterlocking recptacle 23, arms 13 a and 13 b may be separated from eachother to facilitate dissassembly of retractor 10 and thereafter removalof the sparated parts of retractor 10 from the patient's body, as willbe discussed in further detail hereinafter. The single interlockingreceptacle 23 configuration shown in FIG. 3A is illustrative only andadditional interlocking receptacles 23 may be defined at distal end 14(see FIG. 2) for receiving a retractable pin therein to maintain arms 13a and 13 b in the interlocked position.

FIGS. 4 and 4A show an embodiment of retractor 10 having at least oneinterlocking receptacle 23 defined substantially displaced from thecenterline of retractor 10. In this embodiment, tether 19 may beutilized to remove pin 15 from interlocking receptacle 23 insubstantially the same manner as discussed above with reference to FIG.3A. By defining interlocking receptacle 23 substantially displaced fromthe centerline of retractor 10, removal from and/or insertion intointerlocking receptacle 23 of pin 15 may be achieved withoutinterference from structures placed along the centerline of retractor 10during operation thereof (e.g., within slot 17 and/or through opening 7at distal end 14) such as, for example, a pedicle screw or rod, as willbe discussed in detail hereinafter. In this embodiment, optional relieffeatures may be particularly desireable to allow flexing of the portionof the retractor extending underneath the screw assembly as removalforce is applied to remove the retractor from the screw.

Referring now to FIG. 5, one or more optional tubes 24 are definedthrough the longitudinal cross-section of retractor blades 8 a, 8 b.Tubes 24 may be defined along the entire length of retractor blades 8 a,8 b and are adapted to accommodate optical fiber (not shown)therethrough. The optical fiber is in optical communication with anysuitable energy source known in the art (not explicitly shown) andutilized to illuminate the length of retractor 10, or any particularportion thereof, from proximal end 12 along continuous slot 17 to distalend 14. Additionally or alternatively, tubes 24 may be formed from anoptically transmissive material, as is known in the art and coupled to alight source. A suitable light source may include a light emitting diode(LED).

Retractor 10 is formed from a suitable biocompatible material having thedesired physical properties. That is, retractor 10 is formed of abiocompatible, sterilizable material in a suitable configuration andthickness so as to be sufficiently rigid to be held on the screw whendesired during insertion and a surgical procedure and to provideretraction of tissue, and yet is sufficiently bendable to be spreadapart to provide retraction and to be removed from the screw asnecessary and appropriate. It is contemplated that retractor 10 may beformed from metal or plastic. Any maleable, bendable, flexible, orotherwise formable material, including metals and plastics andcomposites, known in the art may be used, such as titanium, titaniumalloy, surgical stainless steel, nickel titanium alloys, shape memoryalloy, polypropylene, polyethylene, polycarbonate, silicone,polyetheretherrketone,etc. If the retractor is made from a conductivematerial, a non-conductive coating may be applied to the surface ofretractor 10 to allow for electrical stimulation of threaded screw 40(FIGS. 6-8) without shunting of current through retractor 10. Anysuitable non-conductive dielectric material known in the art may beapplied to retractor 10 to achieve this purpose. Retractor blade 8 a isbendable away from the centerline of retractor 10 in response to appliedforces, wherein retractor blade 8 a bends at living hinge 4. Retractorblade 8 b is pivotal away from the centerline of retractor 10 inresponse to applied forces, wherein retractor blade 8 b pivots at truehinge 5. Bending and/or pivoting retractor blades 8 a, 8 b away from thecenterline (i.e. radially outwards) creates a larger opening throughretractor 10 and also acts to retract the surrounding tissue at theselected surgical site. Installation and use of retractor 10 in surgicalprocedures will be discussed in detail hereinafter. As will beappreciated, a malleable material is necessary if a living hinge is tobe used, whereas a rigid material for the retractor blades may be usedif a true hinge is used.

In FIGS. 6-8, retractor 10 is illustrated in an assembled condition witha pedicle screw 40. Pedicle screw 40 extends through opening 7 such thatthreads of pedicle screw 40 extend beyond distal end 14 for insertioninto a target site in a bone (e.g. a vertebral body). As shown in thefigures, when pedicle screw 40 is inserted in retractor 10, a head 42(FIG. 7) of pedicle screw 40 mates with the interior geometry of distalend 14. As shown, rod receiving passage 44 of pedicle screw 40 alignswith opening 17 between retractor blades 8 a, 8 b facilitating theinsertion of a rod 3 (FIG. 9) into screw head 42. In addition, pediclescrew 40 is pivotable about the longitudinal axis of retractor 10allowing retractor 10 to be attached in a first angular orientation withrespect to the vertebral body, but pivotable about pedicle screw 40increasing the amount of tissue that may be retracted using retractor10. As will be appreciated, the pedicle screw may be cannulated suchthat it may be translated along a guide wire, thereby facilitatinginsertion of the pedicle screw and the minimally invasive retractor intothe work site.

It is contemplated that any of the retractors embodied herein may beformed of a bendable resilient material such that when externalspreading forces (i.e. from a Gelpi retractor or the physician's hands)are removed, the retractor blades will return towards their initialposition (e.g., substantially parallel to the centerline). It is alsocontemplated that any of the previously disclosed retractors may beformed of a bendable non-resilient material such that when the externalspreading forces are removed, the retractor blades resist returning totheir initial position and remain in the retracted position.

A method for use of the presently disclosed system will now be describedwith reference to FIG. 9. Retractor 10 is assembled with pedicle screw40 as shown in FIGS. 6-8. The assembled apparatus is inserted into anincision through the patient's skin S and muscle/fat tissue T such thatpedicle screw 40 is subsequently threaded into a vertebral body V. Oncethe desired number of screws with retractors 10 are affixed to vertebralbodies V, retractor blades 8 are spread and/or pivoted apart to retractskin S and tissue T to create a retracted area at the target site. Rod 3is inserted in passage 18 when passage 18 is in an expanded state (i.e.,tissue has been retracted). In a preferred method, the rod may beinserted along a path from one screw head to another, possiblysubcutaneously such that it may be secured to fastening regions ofpedicle screws in adjacent vertebral bodies. The retractors of thepresent disclosure are well suited for such a technique due to theunique access provided. Once the screw-rod construct is complete,retractor 10 is removed from the patient as described above by removingthe pins holding the retractor together. The separated portions may bemoved away from the center line of the screw to provide clearance aroundthe screw head, and then pulled out of the incision. This may be done byhand or with suitable gripping tools. To the extent relief regions areincluded, a retractor extracting tool may be used to promote flexing orseparation of relief regions R to facilitate removal of the retractor10. An example of a retractor extracting tool is described in U.S.patent application Ser. No. 11/528,223 (referenced hereinabove).

The physician may remove retractable pin 15 proximally from pinreceptacle 23 using tether 19 or an elongated tool, as indicated bydirectional arrow A (FIG. 3A) and separate arms 13 a, 13 b at pinreceptacle 23, thereby allowing proximal movement of the arms 13 a, 13 bradially away from the centerline of retractor 10, as indicated bydirectional arrows C and D (FIG. 3A). As such, retractor 10 is separatedfrom pedicle screw 40 without imparting significant downward orrotational forces against the patient's body. Retractor 10 may then beremoved from the patient and this process may be repeated for eachinstalled retractor.

It is envisioned that the retractor is utilized, but not limited to, amethod whereby an initial incision is made in the skin of approximately10-15 mm in length. Surgeon preference will dictate the need for one ormore stages of dilators or scalpel blades to aid in expanding the woundbefore introducing one or more retractors in combination with pediclescrews. Normal surgical techniques may be used to close the incision(s).

It is also contemplated that the retractor may be manufactured frommedical grade metal or composites of metal. A metallic part utilizessuch materials as, but not limited to, aluminum, stainless steel,nickel-titanium, titanium and alloys thereof. In addition, the parts mayhave a reflective or non-reflective coating to aid in increasingvisibility in the wound and may have an artificial lighting feature.

It will be understood that various modifications may be made to theembodiments of the presently disclosed retraction system. Therefore, theabove description should not be construed as limiting, but merely asexemplifications of embodiments. Those skilled in the art will envisionother modifications within the scope and spirit of the presentdisclosure.

As with any surgical instrument and implant, the retractors must havethe ability to be sterilized using known materials and techniques. Partsmay be sterile packed by the manufacturer or sterilized on site by theuser. Sterile packed parts may be individually packed or packed in anydesirable quantity. For example, a sterile package may contain one or aplurality of retractors in a sterile enclosure. Alternatively, such asterile surgical kit may also include one or a plurality of bone biopsyneedles guide wires, sterile cannulated scalpels, dilators, rods, orother surgical instruments.

The blades may be made of a light transmitting material. The retractormay include a light guide system. The light guide system has an inputadapter to receive light from a light source and one or more lightemitting surfaces to illuminate the surgical field.

It will be understood that various modifications may be made to theembodiments of the presently disclosed retraction system. Therefore, theabove description should not be construed as limiting, but merely asexemplifications of embodiments. Those skilled in the art will envisionother modifications within the scope and spirit of the presentdisclosure.

For example, while the foregoing description has focused on spinesurgery, it is contemplated that the retractors and methods describedherein may find use in other orthopedic surgery applications, such astrauma surgery. Thus, where it is desired to insert a screw or pin intobone in a minimally invasive manner, or otherwise to access a surgicaltarget site over a guidewire, the dilator, scalpel and retractors (orsome of them) of the present disclosure may be used, with or without abone screw.

Further still, it will be appreciated that the pedicle screw may becannulated such that it may be translated along a guide wire, therebyfacilitating insertion of the pedicle screw and retractor. In addition,it is contemplated that conventional insertion tools or those disclosedin U.S. patent application Ser. No. 12/104,653, filed on Apr. 17, 2008(U.S. Patent Application Publication No. 2008/0262318), the entirecontents of which are hereby incorporated by reference may be used inconjunction with the presently disclosed retractor and pedicle screws.

1. A surgical retractor comprising: a pair of opposed elongate members;a coupling region disposed at one end of the surgical retractor andoperably coupled to the pair of opposed elongate members, the couplingregion having an opening located at a distal end thereof and at leastone interlocking region adapted to permit selective separation of thepair of opposed elongate members; and at least one flexible jointcoupling each elongate member to the coupling region.
 2. The surgicalretractor of claim 1, wherein the flexible joint is a living hinge. 3.The surgical retractor of claim 1, wherein the flexible joint is a truehinge.
 4. The surgical retractor of claim 3, wherein the true hingeincludes a pivot pin.
 5. The surgical retractor of claim 1, wherein theinterlocking regions include aligned openings therethrough.
 6. Thesurgical retractor of claim 5, further including a pin extending throughthe openings through the interlocking regions for releasably securingthe pair of elongated members together.
 7. The surgical retractor ofclaim 1, wherein at least one of the elongate members is formed from amaterial selected from the group consisting of: titanium, titaniumalloy, surgical stainless steel, and shape memory alloy.
 8. The surgicalretractor of claim 1, wherein at least one of the elongate members isformed from a material selected from the group consisting of:polypropylene, polyethylene, polycarbonate, silicone, andpolyetheretherketone.
 9. A method of retracting tissue comprising thesteps of: inserting a surgical retractor into an incision in a patient'sskin; moving opposed blades of the surgical retractor away from acenterline thereof, thereby enlarging the incision; separating theopposed blades of the surgical retractor; and removing the separated,opposed blades of the surgical retractor.
 10. The method of claim 9,further including the step of installing a guidewire into a vertebralbody.
 11. The method of claim 9, wherein the step of separating theopposed blades of the surgical retractor includes decoupling the opposedblades by removing a pin.
 12. The method of claim 9, wherein the step ofinserting the surgical retractor further includes a bone screw extendingfrom a distal portion of the retractor.
 13. The method of claim 10,wherein the step of inserting the surgical retractor further includes acannulated bone screw extending from a distal portion of the retractorand receiving the guidewire through the screw cannulation.
 14. Asurgical retractor comprising: a pair of opposed first and secondelongate members; a coupling region disposed at one end of the surgicalretractor and operably coupled to the pair of opposed elongate members,the coupling region having an opening located at a distal end thereof;and at least one hinge having a hinge pin connecting said first elongatemember to said coupling region.
 15. The surgical retractor of claim 14,further comprising a second hinge connecting said second elongate memberto the coupling region.
 16. The surgical retractor of claim 15, whereinthe second hinge is a living hinge.
 17. The surgical retractor of claim15, wherein the second hinge includes a hinge pin.
 18. The surgicalretractor of claim 14, wherein the coupling region further includes atleast two interlocking portions.
 19. The surgical retractor of claim 18,wherein the interlocking portions include aligned openings therethrough.20. The surgical retractor of claim 19, further including a pinextending through the openings through the interlocking portions forreleasably securing the pair of elongated members together.
 21. A methodof retracting tissue, comprising the steps of: inserting a surgicalretractor into an incision in a patient's skin, the surgical retractorhaving a pair of opposed blades and a coupling region disposed at oneend thereof, the coupling region operably coupled to the pair of opposedblades and having an opening located at a distal end thereof and atleast one interlocking region adapted to permit selective separation ofthe pair of opposed blades; flexing the opposed blades of the surgicalretractor away from a centerline thereof, thereby enlarging theincision; moving the surgical retractor proximally such that thecoupling region separates at the at least one interlocking region awayfrom the centerline of the surgical retractor; separating the opposedblades of the surgical retractor; and removing the separated, opposedblades of the surgical retractor.
 22. A method of performing spinesurgery comprising the steps of: a) providing at least two retractorassemblies, each retractor assembly including a pair of opposingelongate members and at least one interlocking region located at adistal end thereof, the pair of opposing elongate members being flexiblyand releasably coupled to a pedicle screw; b) securing the first screwto a portion of a first vertebral body; c) retracting tissue using theat least one elongate member of the first retractor; d) securing thesecond screw to a portion of a second vertebral body; e) retractingtissue using the pair of opposing elongate members of the secondretractor; f) inserting a rod between the first and second screws; g)securing the rod to the first and second screws; h) moving the surgicalretractor proximally such that the pair of opposing elongate membersseparates along the at least one interlocking region away from thecenterline of the surgical retractor; and h) removing the elongatemembers from the pedicle screws.